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Maintenance Tips

Horiz stab trip question
Author Last Post
Glad to see this thread has resurfaced with some very good ideas. Pulling opposite force on the wheel during trimming works very well. I have noticed that in the cold weather my trim wheel slightly slips to nose up when going fast like in a descent. Could this be due to the fact that the cable tension might be slightly looser due to the airframe shrinkage in cold temps?

Tom
 
Glen,

No spacers. Just a sprocket, shaft, and a few roll pins. 

My jack screws were good. I simply removed the rest of the slop from the system and it worked as designed. You just need to get a MX Manual, Parts Manual, McFarlane’s diagrams and then start studying. It’s not rocket surgery. 

Paul 

image1.png

Sent from my iPhone

On Dec 18, 2017, at 20:48, Glen Whitener (gwhitener@sbcglobal.net) <mailer@mail2.clubexpress.com> wrote:


Paul
Thanks for the insight.  I knew there were spacers or something that went on the trim wheel shaft but I havent seen a good drawing of the the parts on or around the trim wheel mechanism.  Someone ingeniously used a large cable tie to take up some slack. My mechanic said he thought I might need a new cable tie.

grwmo
 

Paul
Thanks for the insight.  I knew there were spacers or something that went on the trim wheel shaft but I havent seen a good drawing of the the parts on or around the trim wheel mechanism.  Someone ingeniously used a large cable tie to take up some slack. My mechanic said he thought I might need a new cable tie.

grwmo
 
Grwmo,

I have a 56 180. I too have the slick trim wheel with no clicker. Trim used to walk all the time above 140 mph IAS and in turbulence. 

I replaced the following:

Trim wheel shaft and sprocket from McFarlane. 

Bushings and spacers for horizontal attach point (see below). 

image1.jpeg

Tightened trim cable to upper limit of spec 22.5 lbs. 

image2.jpeg

Stab is tight and NO MORE TRIM WALKING! 😁. Wish I had done it years ago. 

Paul Brown
N6503A

Sent from my iPhone

On Dec 15, 2017, at 14:04, Glen Whitener (gwhitener@sbcglobal.net) <mailer@mail2.clubexpress.com> wrote:

I was talkinlbg with Cessna tech support yesterday about the secondary seat restraint but during the call I asked the Engineer about the lubrication recommended for the jack screws.  He looked at the military specs and extrapolated that number into Aeroshell 6.  He said this was a grease similar to wheel bearing or other grease, but it was not an oil.  I am having a few issues with my stabilizer and I have wondered about the type of grease and if it might make a difference in the trim.  Mine will move some if it is bouncy.  I intend to tighten the cables, although they are about 20 lb tension according to my gauge/tester.  The tech said that 20lb was about right but I think more tension creates a little more resistance or friction in the jack screws which I need.  My 1953 180 has a smooth trim wheel with no clicker or resistance caused by a clicker as most do on the passenger side.

If you have any thoughts on this please post them.
grwmo
 
Jack screw system. . .
I made a tiny slit in the top of the leather "glove" and squirt in heavy duty marine lube used in lower ends of in-and-out drives.  Usually comes in a tube. 
After application, I do a "milk the cow" routine on the leathers to distribute the grease throughout the jack shaft threads.
This lube is very good stuff as it has to work well in the marine gear environment and will not harden.
 
Also, key is to have cables set to the upper side of the Cessna tension specs.
 
Another idea, when changing pitch trim while at cruise speeds, move the yoke first in the opposite direction, then roll the pitch trim wheel desired  That takes a lot of the strain off the trim pitch cabling system.
In our legacy aircraft, I believe it is fairly common, when in turbulence, to maybe see the pitch trim do a few "click" wheel self changes.
 

----- Original Message -----
Sent: Friday, December 15, 2017 2:04 PM
Subject: re: Horiz stab trip question <<$186711619809$>>

I was talkinlbg with Cessna tech support yesterday about the secondary seat restraint but during the call I asked the Engineer about the lubrication recommended for the jack screws.  He looked at the military specs and extrapolated that number into Aeroshell 6.  He said this was a grease similar to wheel bearing or other grease, but it was not an oil.  I am having a few issues with my stabilizer and I have wondered about the type of grease and if it might make a difference in the trim.  Mine will move some if it is bouncy.  I intend to tighten the cables, although they are about 20 lb tension according to my gauge/tester.  The tech said that 20lb was about right but I think more tension creates a little more resistance or friction in the jack screws which I need.  My 1953 180 has a smooth trim wheel with no clicker or resistance caused by a clicker as most do on the passenger side.

If you have any thoughts on this please post them.
grwmo

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I was talkinlbg with Cessna tech support yesterday about the secondary seat restraint but during the call I asked the Engineer about the lubrication recommended for the jack screws.  He looked at the military specs and extrapolated that number into Aeroshell 6.  He said this was a grease similar to wheel bearing or other grease, but it was not an oil.  I am having a few issues with my stabilizer and I have wondered about the type of grease and if it might make a difference in the trim.  Mine will move some if it is bouncy.  I intend to tighten the cables, although they are about 20 lb tension according to my gauge/tester.  The tech said that 20lb was about right but I think more tension creates a little more resistance or friction in the jack screws which I need.  My 1953 180 has a smooth trim wheel with no clicker or resistance caused by a clicker as most do on the passenger side.

If you have any thoughts on this please post them.
grwmo
 
I have seen installations where the spring around the jack screw is missing.  The spring is there to help take the load off of the jackscrew when aerodynamic loads are high,  Should be able to feel the spring through the boots.
 
Tom,
. . . suggest always using the yoke to set/hold your desired down pitch and then roll in the nose down trim to hold the setting.  Using the trim alone for adjusting nose down is very hard on all the trim components.  Nose down, at speed, is normally heavy.
 

----- Original Message -----
Sent: Saturday, January 21, 2017 2:29 PM
Subject: Horiz stab trip question <<$164588227805$>>

Thank you all for all the help on getting my newly acquired 73 185 up to speed.
The horiz trim wheel was mostly fairly easy to run fore and aft to stops on the ground. We lubed all hinges and the jack screws with a needle. It runs very free now end to end on the ground. In flight if I exced 150 or so it becomes VERY difficult to trim nose down. I have read all the posts and understand this is an issue. We did not check the eccentric bushing alignment however.
Could these cause that excessive difficulty in trimming nose down at speed?

Tom



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Last time it was hard to trim I lubed the crap out of both jack screws but that didn't cure the issue so pulled them out & found one of the jack screws bent.After replacement all was back to normal.
if you have no history on the back end then check alignment first,suspect mine got bent removing jack screws to replace roll pins.

Daryl
 

Nose down trim being difficult at speed = typical. You can offload the trim by applying a bit of pressure on the yolk when trimming at speed.

 

I try to roll in approximate cruise trim before leveling off (while at climb speeds) to minimize the stress on the overall system.

 

Sheared roll-pin = been there, done that.

 

From: mailer@mail2.clubexpress.com [mailto:mailer@mail2.clubexpress.com]
Sent: Saturday, January 21, 2017 4:29 PM
To: Maintenance Tips <MaintenanceTips@skywagons.club>
Subject: Horiz stab trip question <<$164588227805$>>

 

Thank you all for all the help on getting my newly acquired 73 185 up to speed.
The horiz trim wheel was mostly fairly easy to run fore and aft to stops on the ground. We lubed all hinges and the jack screws with a needle. It runs very free now end to end on the ground. In flight if I exced 150 or so it becomes VERY difficult to trim nose down. I have read all the posts and understand this is an issue. We did not check the eccentric bushing alignment however.
Could these cause that excessive difficulty in trimming nose down at speed?

Tom

 




Thank you all for all the help on getting my newly acquired 73 185 up to speed.
The horiz trim wheel was mostly fairly easy to run fore and aft to stops on the ground. We lubed all hinges and the jack screws with a needle. It runs very free now end to end on the ground. In flight if I exced 150 or so it becomes VERY difficult to trim nose down. I have read all the posts and understand this is an issue. We did not check the eccentric bushing alignment however.
Could these cause that excessive difficulty in trimming nose down at speed?

How do you edit the subject line? Sorry I tried to edit trip to trim but couldn't

Tom
 
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